The present invention relates generally to power supplies and more specifically to battery-powered power supplies for electronic devices.
In a wide variety of environments it may be desirable to employ a battery-powered power supply for the purpose of making stored electrical energy available to an electronic device. In many cases, this control over the provision of battery energy may consequently be an effective means to activate and deactivate the electronic device. In some cases, the battery and its respective resistive load may not be easily accessible. One example of such a case may be when the resistive load and the battery are enclosed in a protective coating such as a potting material in order to resist adverse effects from an operating environment. Another example of such a case may be a downhole processor in a tool string with a single port of communication through the tool string.
Several battery power source apparatuses are known in the art. For example, U.S. Pat. No. 5,945,745 discloses an activation control for an automotive electronic module. A dimming circuit provides a dimming signal when a demand for energy is made, such as when headlights are turned on with an ignition switch turned off. The detector senses the dimming signal and operates a battery switch to power up a microprocessor controller from an unpowered state to control operation of the module when the demand for energy is made. There is no sleep mode. The microprocessor controller is only powered for as long as the dimming signal is present.
U.S. Pat. No. 4,455,623 discloses an apparatus for decreasing current consumption of microprocessors in battery-energized systems. The apparatus comprises a switch which connects it to the electrical supply only when a control signal is received which indicates that the microprocessor is to execute a program. For programs whose execution time is greater than the duration of the control signal, the microprocessor supplies a signal to the switch keeping it in the conductive state until the program has been fully executed. In this invention the microprocessor is only powered for as long as a control signal or signal from the microprocessor itself is present.
U.S. Pat. No. 4,279,020 discloses a power supply circuit for a data processor. The power supply circuit comprises a power up circuit comprising a single pair of complementary transistors arranged so that an output electrode of each transistor is connected to an input electrode of the other transistor. The power up circuit is latched on responsive operation of a data input circuit and supplies power to the processor when latched.
U.S. Pat. No. 3,535,560 discloses a multisection computer with operating power supplied intermittently to each of the several sections. Power is switched to the sections by the emitter-collector path of a transistor that remains on after a control waveform has terminated.